Hi! I love soundtracks as well and would love to join this club!
My top 3 soundtracks are:
1. While You Were Sleeping - I find it very comforting for some reason
2. Hotel del Luna - Heize's "Can you see my heart" is by far my favorite
3. Snowdrop - If you're with me is one of my favorite ost among all ost, I love the piano that plays throughout the whole song (I want to learn how to play it)
I have also listened to some OSTs like Goblin OST and Our Beloved Summer OST but I haven't watched those dramas yet so, even though I really like their OSTs I have decided not to include them on my list.